SYNOPSIS Five of 65 patients referred for electrodiagnosis because of clinical evidence of carpal tunnel syndrome were found to have near normal latency on proximal stimulation of the median nerve, although the distal motor latency was prolonged. In one patient, the proximal latency was actually shorter than the distal latency. The failure of the proximal latency to be prolonged in proportion to the distal latency results in a spuriously high apparent conduction velocity in the forearm segment of the nerve. This value may even exceed the conduction velocity of the corresponding nerve segment in the unaffected arm. Stimulation studies on the ulnar nerve reveal that this disparity is the result of some of the median nerve fibres destined for the thenar muscles taking an aberrant course through the ulnar nerve and thus escaping compression at the wrist. A median-ulnar communication in the forearm, the 'Martin-Gruber' anastomosis, may occur in up to 15 % of the population. The presence ofthe Martin-Gruber anastomosis in patients with carpal tunnel syndrome results in a partial or total sparing ofthenar muscles from denervation and the paradoxical recording of normal proximal latencies in the median nerve when the distal latency is prolonged.A communication between the median and ulnar nerves in the forearm, often known by the eponym Martin-Gruber anastomosis, occurs in about 15 % of the normal population (Mannerfelt, 1966). This anomaly is asymptomatic and often goes undetected. However, with injuries or other disturbances of the ulnar or median nerves, the presence of the anomaly is revealed by the unusual distribution of the motor and/or sensory deficit. It is conceivable that such an anomaly could alter the electroneurographic findings in cases of carpal tunnel syndrome. The authors have examined five such individuals in whom the most striking finding was a near normal median nerve proximal latency in the

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The sciatic nerve is by far the most common nerve accidentally injured during intramuscular injection. Despite its close proximity to the sciatic nerve, however, injury to the posterior femoral cutaneous nerve is apparently quite rare. In this report, clinical features of a patient with isolated injection injury to the posterior femoral cutaneous nerve are described.